Designing my grey water system in frost free climate, and math questions!

Xisca Nicolas

pollinator

Posts: 1277

Location: La Palma (Canary island) Zone 11

22

posted 1 year ago

1

Any input welcome so that I make it right from the start, thanks!
We started just today to dig the place where 2 sources of grey water will meet, and there the 1st question:

A pipe will come from the main home, and I have to join there the pipe that will come from a summer shower + washing machine.
I guess a T can be stuck and difficult to clean, so we think about constructing a little "box" with cement.
Both pipes would arrive in there, and 1 will come out.
What would be the right size?
(especially because of the washing machine)
What cleaning should I expect to do in there?
I think to put the out-pipe at bottom level, so that no water stays in, and thus no smell... Am I right?

About pipes size, several persons tell me different things about the diameter of the pvc grey pipes I have to put.
Some say that the smallest the better, so that the pressure of the water is higher and removes well all dirt. This would be the 50mm diameter (I think 2 inches).
Some say to put larger pipes, or put the small one as far as this little connecting box, and put a larger diameter in the way out to the tank.
So I am a little lost...

About distance, it will be 10meters between the 1st and second part of the house, and then nearly as much to reach the tank.
The ground is naturally a little steep all the way, which makes it easier.
What would be the correct/best % to be respected on the way?

The tank is already constructed, I guess half cubic meter, in cement.
I have time to think about the plants I will put in there...
The question would be at the moment about making a 2nd tank, or if it can go directly to the plants.
Down there I have veggies but mainly I would target the hungry/thirsty banana trees.

I also have questions about the pipe coming out of there: at what distance from the bottom should it go out, and should I put 2 at different level?
My question relates to the watering of the plants + the eventual cleaning that has to be done.

All about mathematic questions!
Thanks for help, I was so glad to see that Laura was invited today about just what I needed!

I should add that I have no special local requirement, everyone is doing what he wants here,
if you saw the installation of the former owner, with black water going out just between rocks... you'd understand why I am sooo happy to change this!
First of course with a compost toilet, so that I will recycle only grey water.

I also discovered a "spring" in my ground... that smells stange... This surely comes from my upward neighbours!
And they have canes, bamboo etc, which does not prevent the water to escape.
I chose to consider that I was lucky to receive at the same time water + nutrient....
I am in a dry climate!

Hi,
As I'm sure you know there are many different ways to reuse greywater. Since you're in the middle of the project my suggestion may not be arriving at the best time....

It's usually better to keep your greywater fixtures separate, and install smaller, independent systems. You can irrigate plants near to each fixture. By doing this you typically save money, use less pipes/resouces, and can irrigate a larger area of the landscape. The exception to this is if you're going to be installing a pumped system (but it doesn't sound like you are).

So, my suggestion would be to install a system near the washing machine, then another one near the shower, and another from the fixtures in the second house.

It sounds like you can slope the pipe and install a gravity flow system, called a "branched drain" system. You can use organic matter under each outlet to filter the greywater (in a mulch basin) and plant adjacent to the basin.

Or, to answer your first question, if you want to combine the flows you'll want to use 2" pipe at least, and use a "combo" fitting, which prevents clogging. If you can't find a "combo" you can buy a wye fitting with an 1/8th bend (see image). The pipe joining the first pipe will enter the bend of the fitting.

Good luck with you system! Sounds like you're going to be making a big improvement on the previous system.

611942101702lg.jpg

Co-founder: Greywater Action, www.greywateraction.org
Author: The Water-Wise Home: How to Conserve, Capture, and Reuse Water in Your Home and Landscape

Xisca Nicolas

pollinator

Posts: 1277

Location: La Palma (Canary island) Zone 11

22

posted 1 year ago

Well, I did not chose this way of doing because I cannot really.
I had seen this page before, and I have seen this system with "direct delivery" to plants.
So I still have the same questions!

My concern is only about the part that is outside, as everything is done inside, with the water coming out at ground level.

My place is terraced, and the home place is along a path that goes down to the garden.
There is nothink to irrigate in the path, there is a wall down there,
so I want to go as far as the place where this wall finishes.

That would be ugly to have pipes going down the wall + heat and sun on them...

A pipe will come from the main home, and I have to join there the pipe that will come from a summer shower + washing machine.
I guess a T can be stuck and difficult to clean, so we think about constructing a little "box" with cement.
Both pipes would arrive in there, and 1 will come out.
What would be the right size?
(especially because of the washing machine)
What cleaning should I expect to do in there?
I think to put the out-pipe at bottom level, so that no water stays in, and thus no smell... Am I right?

About pipes size, several persons tell me different things about the diameter of the pvc grey pipes I have to put.
Some say that the smallest the better, so that the pressure of the water is higher and removes well all dirt. This would be the 50mm diameter (I think 2 inches).
Some say to put larger pipes, or put the small one as far as this little connecting box, and put a larger diameter in the way out to the tank.
So I am a little lost...

I would use the fitting I showed in the previous post, there shouldn't be clogging, but you also should include a plumbing cleanout after every 100 feet of pipe, or after 135 degrees of bend (for example, after a 90 and a 45 bend, you'd want to add a clean-out).

About distance, it will be 10meters between the 1st and second part of the house, and then nearly as much to reach the tank.
The ground is naturally a little steep all the way, which makes it easier.
What would be the correct/best % to be respected on the way?

2% of the correct slope, you can do more if the ground is sloping more steeply. This slope is designed for combined wastewater and greywater has much less organic material than combined wastewater so it is less likely to clog.

The tank is already constructed, I guess half cubic meter, in cement.
I have time to think about the plants I will put in there...
The question would be at the moment about making a 2nd tank, or if it can go directly to the plants.
Down there I have veggies but mainly I would target the hungry/thirsty banana trees.

I would use organic material to create mulch basins and irrigate the banana's directly. The maintenance is easier on a much basin than with a tank.

I also have questions about the pipe coming out of there: at what distance from the bottom should it go out, and should I put 2 at different level?
My question relates to the watering of the plants + the eventual cleaning that has to be done.

I'm not sure what kind of substrate you plan to use in the tank, but what ever you use I would avoid having any standing water. It sounds like you're planning to plant in the tank, so I imagine you'll use a substrate like gravel and plant into that. In this case make sure the outlet is lower than the inlet so the water level is below the top of the gravel.

If the tank is more of a surge tank, where the water just passes through it, then try to put the outlet so there is minimal standing water (put it as low as possible but high enough so you can direct the outlet to the area you need).

Good luck with your project!

Co-founder: Greywater Action, www.greywateraction.org
Author: The Water-Wise Home: How to Conserve, Capture, and Reuse Water in Your Home and Landscape

Xisca Nicolas

pollinator

Posts: 1277

Location: La Palma (Canary island) Zone 11

22

posted 1 year ago

Laura Allen wrote:I would use organic material to create mulch basins and irrigate the banana's directly. The maintenance is easier on a much basin than with a tank.

I'm not sure what kind of substrate you plan to use in the tank, but what ever you use I would avoid having any standing water. It sounds like you're planning to plant in the tank, so I imagine you'll use a substrate like gravel and plant into that. In this case make sure the outlet is lower than the inlet so the water level is below the top of the gravel.

If the tank is more of a surge tank, where the water just passes through it, then try to put the outlet so there is minimal standing water (put it as low as possible but high enough so you can direct the outlet to the area you need).

Good luck with your project!

Thanks!
I will do as you say and direct the water to the plants, with mulch.
So you really oriented me with this answer.
Any drain, gravel etc, would be too much too maintain.

My idea with the little tank (less than 1m3) was to collect the irregular use of water and use it when I want.
and also let the water cool when it is not cold.
How is it done to direct hot water directly?!?!?!?!?!?!

I did not want to plant in gravel, but use water plants.
Now I think I will keep this tank for rain-water.
Just have to solve the hot water question.

My 1st goal was to keep water during wet period, and use it when dry.
But this is too complicated and costly...

By the time hot water has flowed through all the pipes, soaked into the mulch, and then reached the soil it's really not hot anymore (it can be a little warm). I've never seen any problems with using it this way, so
I wouldn't worry about the hot-ness of the water at all!